Sewing machine



April l0, 1945. c. F. RUBEL I SEWING MACHlNE Filed Jan. 3,' 1942 2I Sheets-Sheet l INVENTOH. cfm/w55 E ffl/BEL ATTORNE.

April 10, 1945. c. F. RUBEL SEWING MACHINE Filed Jan. s, 1942` 2 sheets-sheet 2 FIG.6.

A TTORNE Patented Apr. 10, 1945 SEWING MACHINE Charles F. Rubel, Chicago, Ill., assignor to Union Special Machine Company, Chicago, Ill., a corporation of Illinois Application January 3, 1942, Serial No. 425,494

13 Claims.

This invention relates to an improved sewing machine construction. It has particular reference to lockstitch machines and to the operation thereof in the course of tacking or locking the ends of la seam.

In the customary use of lockstitch machines, as heretofore constructed, considerable skill and experience has been required to provide a lock at the end of a seam in a neat and eii'ective manner. The operator has been compelled to exert just the right amount of pressure upon the knee control, or other device, provided for lifting the presser bar so that the pressure of the spring acting on this bar has been relieved just sufficiently to enable appropriate manipulation of the work for tacking purposes. For proper results, this must be accomplished without actually lifting the presser foot from the work. If the presser foot is lifted from the work, the latter has a tendency to follow the needles in their upward movement with the result that drum heading occurs. That is to say, the needle thread loops are not correctly formed so as to be caught properly by the rotary hook, thus causing the skipping of some of the oops.

An object of the present invention has been to provide a simple construction by which tacking may be correctly and expeditiously performed by operators having little or no special skill or experience in performing this type of work. Toward this end a special presser foot construction has been provided which is simple in its use.

Other objects, features and advantages of the invention will appear from the detailed description of an illustrative form of the same which will now be given in conjunction with the accompanyin-g drawings, in which:

Fig. l is a front elevation of the machine with the cover plate of the needle head removed and with a portion of the work support shown in section.

Fig. 2 is la detail view, in elevation, showing the connections between a lifting lever and the presser bar.

Fig. 3 is an enlarged detail, partly in elevation andpartly in section, sho-wing the construction of the presser foot and its connection with the lower end of the presser bar, the parts being shown in their normal, active positions for seam formation.

Fig. 4 is a view similar to Fig. 3 but shows the parts in tacking position.

. Fig. 5 is an exploded, perspective view showing the details of each part of the presser foot, and

Fig. 6 is a side elevation, with portions broken away, showing the complete machine on a reduced scale.

For purposes of illustration, the invention has been shown applied to a machine of the general type disclosed in the Christensen et al. Patent No. 2,113,572, granted vApril 12, 1938. Reference may be had to said patent for further details regarding the construction and operation of -certain of the devices embodied in the machine, such as the stitch-forming and work-feeding devices, which will be but briefly described herein.

Referring now particularly to Figs. 1 and 6, the machine comprises a base portion IU adapted to be suitably mounted in the top of a work table and providing on its upper surface a support for the work to be stitched. Secured to the base portion I0, adjacent one end, is a vertical standard Il, from the topo-f which projects, laterally, an overhanding arm I2 carrying a needle head I3. Within the needle head 'a vertically reciprocable needle bar I4 is provided, this carrying one or more needles I5 at its lower end. The means for reciprocating the needle bar are not shown in the present case but are disclosed in said Christensen et al. patent. These means are driven by suitable connections from the combined hand-wheel and pulley I6 adapted to receive power from any appropriate source. Within the base portion Il) a rotary hook I1 is provided to form a'lockstitch in conjunction with the needle I5. Suitable connections (not shown) are provided from the marin drive shaft carrying the pulley I6 to rotate the rotary hook in synchronism with the voperation of the needle. A throat plate I8 is provided in the work supporting surface of the base portion I0 and the work I9 is vadaptedto be fed over this throat plate by means of a feed dog 20 having portions extending through the usual slots formed in the throat plate. Any suitable means, such as that disclosed in said prior Christensen et al. patent, may be provided for imparting the desired four-motion feed movements to the feed dog 20.

Also mounted for vertical movement within the needle head is a presser bar 2l slidable in a bearing in the lower portion 22 of the needle head and in a bearing provided by the inner surface of a sleeve 23 having screw-threaded engagement with a portion 24 at the top of the needle head. A thumb screw 25, carried by the upper end of the sleeve ,23, lenables .the vertical adjustment of this sleeve within the needle head fnameL About midway of the length of the presser bar there is secured a block 26 which extends laterally into a slot formed in the side wall of the needle head,

r the upper end of this slot being indicated at 21.

A spring 28, surrounding the presser bar, bears at its upper end against sleeve 23 and at its lower end against the top of the block 25. The spring thus urges the presser bar downwardly by a force which may be varied to suit particular requirements by proper adjustment of the sleeve 23.

Beneath the block 26 there is slidably mounted on the presser bara sleeve or collar 29 having .at its upper end a laterally extending arm 30 cooperating with the guide slot 21 in the side wall of the needle head. Arm 30 is parallel y with and is normally spaced slightly below the arm 26 but it is adapted to be lifted into yengagementwith the latter arm and to be then lifted further to elevate the presser bar. For this purpose the sleeve 29 has, at its upper end, a rearwardly extending arm 3l to which is pivotally connected a link 32 having its upper end pivotally attached to a forwardly extending arml of a two-armed lever 33. This lever is attached to the frame of the machine by .a pivot screw 34. A spring 35 connected to lever 33 and to a pin .on the machine frame :normally serves to rock the lever in aclockwise direction (Figs. l

and 6i and maintains the arm 30 in its spaced relation to the arm 2G. "At this time the arm 30 rests upon the upper surface of a cam member 3.6 pivotedV at 31 upon the needle head and adapted to be rocked manually by .a lever 38.

4When lever 38 isylifted bythe operator; the

arm 30 will be raised against the arm 26 and the presser bar' will thenv be; raised to lift the presser foot, to' be later described, from the work. The form of the cam member 36 is such that it will hold 'the presserbar in its elevated a pin 43 adapted to engage the curved upper surface of a rod or-arm 44 secured to a rock shaft 45 mounted on a 'bracket secured to the underside of the table which carries the machine. yAt a convenient point, the rock shaft 45 has secured thereto a downwardly extending arm 45 whichv carries a kneeoperated member 41 adapted to be vengaged by theleft knee of the operator of the machine. v As the knee plate 41 is shifted toward the left (Fig. 6), the yshaft 45 will be rocked clockwise to rock the .arms 40 and `42, aswell as the lever 33, counter-clockwise, thus lifting the sleeve 29, and hence the presser ban'against the action -of the spring 28.

At the lower end of the presser bar there is secured a presser foot of special construction. This .presser foot has -a shank 48 adapted to be secured to theA lowerend of the presser har by means of a screw 49.-- A blocklike extension 55 of the shank has a vertically disposed `opening in which .is slidably mounted a stern l formed as an integral. upward extension of a block 52. A screw 53 secured tothe upper end `of the stem 5l has .an enlarged head .adapted to slide in an enlarged recess ,54 .adjacent the top `of the shank extension 5.0. the stem; 5i within an enlarged recess 56 at the bottom .of the extension` 50 urges the stem and block 52 downwardly. `When the presser ,A forwardly I l extending arm lli! of the rock membercarries bar is lifted into the position indicated in Fig. 4, the spring 55 will urge the stem 5i downwardly until the under surface of the headof screw 53 engages the bottom of the enlarged recess 54. In a transverse aperture through the block 52 there is mounted a pin 51 which serves to pivotally attachv to the block a presser foot 58 of any suitable form. At the sides of the presser foot there are integral, upwardly extending ears 59 adapted to straddle the block 52 and to engage the fiat, side surfaces of the extension 50 of the shank. The ears 59 are constantly engaged with the sides ,of the shank A spring 55 coiled about i Vextension and thus prevent relative turning in a horizontal direction between the presser foot and shank. However, relative sliding movement and relative turning in a vertical plane is permitted between the presser foot and shank.

In the normal operation of the machine, the presser bar and the presser foot will assume the relationship indicated in Fig. 3. The under surface 55 of theshank will be brought against the top of the block 52, the spring 55 :being comipressed due to the superior streng-th of the spring 28. Presser foot 58 may, at this time, tilt about the pin 51 in passing over seams in .the work 4as the latter is advanced by the feed dog 28. l'n general the operation will be substantially Ithe same as if the presser foot were pivoted directly upon an integral part of the shank. When the end of the seam is reached, however, and it is desired to perform a tacking operation, the operator will press the kneeA against the knee plate 41 and shift the latter suiiiciently to raise the presser bar into any position between that indicated in Fig. 3 and that indicated in Fig. 4. The pressure of the spring 28 will be completely offset and the presser foot will be held against the work merely by the force of the spring 55. This greatly reduced pressure will be sufficient to prevent the drumheading evil, which the invention is intended to eliminate, but it will not interfere with the Arelatively free movement of the work by hand.

The operator, in utilizing the improved construction, need not shift the knee control with any particular precision. Considerable latitude is permitted in the extent of movement of this control member. It is sufficient merely to relieve or offset the pressure of the spring 28 without, in fact, lifting the presser' bar at all, and it is also entirely satisfactory -to lift the presser bar a substantial extent, i. e., approximately the ampunt of the relative movement between the shank 48 and the stem 5l, permitted by the block 52 and the head of screw 53. The clearance between the shank and the head of the screw should not be taken up completely, since then the pressure of even the spring 55 would be removed from the presser foot. Of course, the presser bar may be lifted to any point intermediate the two extreme positions .shown in' Figs. 3 and 4. No special-aptitude or experience on the part of the operator will be required to accomplish this anda substantially uniform, light pressure on the presser foot is insured for tacking purposes at all times. Whenever it is desired to disable the presser foot completely, the presser bar may be raised high enough to lift the presser foot from the `work. This -will be done after the clearance between the head of screw 53 and the bottom of recess 54 has first been taken up. Such lifting of the presser foot may be accomplished either by the knee control or by the lever 38.

Whilean illustrative embodiment of the im'- proved' sewingv machine has been described in some detail, it will be understood that various changes may be madein the construction and arrangement of the parts without departing from the general principles and scope of the invention.

WhatIclaim is:

l. In a sewing machine, a work support, a presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said ban'a block yslidably mounted on said shank, a spring urging said block downwardly on said shank, and a presser member carried by said block, said rst mentioned spring being stronger than the second, said presser bar and shank being normally free to move downwardly until said first mentioned spring forces said block into its uppermost position on said shank in solid vengagement with a surface thereon and retains said presser member yieldingly bythe full force of said rst mentioned spring against work on said support.

2. In a sewing machine, a work support, a presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said bar, a block slidably mounted cn said shank, a spring urging said block downwardly onsaid' shank, and a presser member pivotally mounted on said block, said rst mentioned spring being stronger than; the second, said presser bar and shank being normally free to move downwardly until said first mentioned spring forces said block into its uppermost position on said shank in solid engagement with a surface thereon and retains said presser member-yieldingly by the full force of said first mentioned spring against work on said support.

3. In a sewing machine, a work support, a presser bar, a spring urgingy said presser bar downwardly, a shank attached to the lower end of said bar, a presser foot shiftably mounted on said shank, and a spring urging said presser foot into one position on said shank and serving to hold said foot against work of uniform thickness on said support as the presser bar is raised slightly, said iirst mentioned spring being stronger than the second, said presser bar and shank being normally free to move downwardly until said rst mentioned spring shifts said presser foot into a predetermined position on said shank against the action of said second spring and holds it yieldingly against the work by the action of said rst mentioned spring.

4. In a sewing machine, a work support, a

presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said bar, a presser foot shiftably mounted on said shank, means limiting the movement of `said presser foot relative to said shank in either direction, and a second spring urging said presser foot in one direction relative to said shank, said rst mentioned spring being stronger than the second, the parts being so constructed and arranged that said rst-mentioned spring serves to hold said presser foot normally at its limit of movement in a direction opposite to said one direction against the action of said second spring and to hold the presser foot yieldingly against the work by the action of said rst mentioned spring.

5. In a sewing machine, a work support, a

presser foot relative to said shank'in either di;

rection,' a second spring urging said presser foot in one direction relative to said shank, said rst mentioned spring being stronger than the second, the parts being so constructed and arranged that said first-mentioned spring serves to hold said presser foot normally at its limit of movement in a direction opposite to said one direction against the actionof said second spring and to hold the presser foot yieldingly against the work by the action of said rst mentioned spring, and means operable at will for lifting said presser bar slightly and thereby oisettingthe action of said first mentioned spring, saidA presser foot lthen being urged against the work by said second spring.

6. rIn a sewing machine, a work support, a presser bar, a spring Iurging said presser bar downwardly, a shank attached to the lower. end of said bar, a presser foot shiftably mounted on said shank, means limitingthe movement of said'ipresser foot relative to said shank in either direction, a second spring urging said presser foot in one direction relative to said shank, said first mentioned spring being stronger than the second, the parts being's'o constructed and arranged that said iirst-mentioned spring serves to hold said presser foot'normally at its limit of movement'in a direction opposite to said one direction against the action of said second spring and to hold the presser foot yieldingly against the work by the action ofy said first' mentioned spring and` means operable'at will for lifting said presser bar slightly and thereby olsetting' the action of said rst mentioned spring, said presser foot then be-v ing urged against the work by said second springsaid last 'mentioned means being operable also to lift said presser foot completely from the work.

'7. In a sewing machine, a work support, a presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said bar, a presser foot shiftably mounted on said shank, means limiting the movement of said presser foot relative to said shank in either direction, a second spring urging said presser foot in one direction relative to said shank, said first mentioned spring being stronger than the second, the parts being so constructed and arranged that said rst-mentioned spring serves to hold saidl presser foot normally at its limit of movement in a direction opposite to said one direction against the action of said secondspring and to hold the presser foot yieldingly against the work by the action of said rst mentioned spring, knee actuated means for lifting said presser bar slightly and thereby offsetting the action of said rst mentioned spring while permitting said presser foot to be urged against the work by said second spring, and manual means for lifting said presser bar to disengage the presser foot completely from the work.

8. In a sewing machine, a work support, a

` presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said bar, a carrier shiftably mounted on said shank, stop means for limiting the movement of said carrier in each direction on said shank, a second spring urging said carrier in one direction relative to the shank, and a presser foot pivotally mounted on said carrier, said rst mentioned spring being stronger than said second spring, the parts being so constructed and arranged that said first-mentioned spring serves to force said.

carrier against said stop means in a direction opposed to said-second spring as the presser foot isiurgd' againstwork of uniform" thickness, presser root being held ag'nst'the work-:by the full force of said rst mentioned spring.

9. In a sewing machina'a work support,A a presser bar, a springv urging said" presser bar downwardly, a shank attached to the lower Iend of said bar, a carrier `shiftably mounted on said shank, 'stop means for limitngjthe movement of said carrier `in each direction on said shank, a second spring `urging said carrier in one direction relative to the shank, a'presser foot pivotalh7 ymounted on. said carrier, said rst mentioned spring being stronger than said second spring, the partsbeing so constructed and arranged that said first-mentioned-spring serves to force said carrier against said stop means in a direction opposed to said second spring as the presser foot is urged against `work of uniform thickness. said presser foot being held against the work by the full* force of said' rst mentioned spring, and

y means operable at will for offsetting the force of said iirst mentioned spring while .allowing said second spring to urge said presser foot against the work. n

l0. In a lockstitch sewing machine having a work support, axreciprocable needle and a rotary hook, means for facilitating the locking of the end of a seam which comprises a presser foot',

a plurality of springs normallyacting simultaneously in series relation to urge said presser foot against Work on said support, one of said springs being stronger than another and normally exerting its full effect' upon said presser foot, and means operable vat will for offsetting the action of only said stronger spring.

11. In a lockstitch sewing machine havingA a Work support, a reciprocable needle and a rotary hook, means'f-or' facilitating the locking fof the end of'a seam which comprises 'a' presser foot; a plurality of springs .alternately effective .for urging said presser foot against work-on said support, one of said springs being arranged to exert a greater force than another, and means under control of the operator yfor rendering either of said springs ineiective at will in the 'course of stitching work of uniform thickness.

12. In a lockstitch sewing machine having a work support, a reciprocable needle and a 'rotary hook, means for facilitating the locking of the end of a seam which comprises a presser foot, a plurality of springs alternately effective for urging said presser foot against work on said support, one of said springs being arranged'to exert a .greater force than another, means for varying the force exerted by said one spring, and means under control of the operator for rendering either of said springs ineffective at will in the course of stitching work of uniform thickness.:

13. In a sewing machine, a work support, a presser bar, a spring urging said presser bar downwardly, a shank attached to the lower end of said bar, a member slidably mounted on said f CHARLES F. RUBEL. 

